AFTER MISTAKES OF LAST SEASON, CHARGERS GM SMITH IS ‘LOCKED AND LOADED’ ON 2012

But that depth already has taken a hit in a bad place — left offensive tackle — where gigantic Jared Gaither has been out nearly all summer with back spasms that have shaken the world. It’s all about protecting quarterback Philip Rivers’ blind side, and the young man now doing so is Mike Harris, an undrafted rookie free agent out of UCLA so green he’s solar-powered.

“We had Gaither at No. 1, Brandyn Dombrowski at No. 2, Tyronne Green, who happens to be our starting left guard, at No. 3, and Mike Harris, a rookie we believe is talented and wanted to work with, at No. 4,” Smith says. “So what happens? Dombrowski hurts his foot. Then it’s Gaither’s back. Green is our starting guard. Suddenly we’re already down to No. 4. So, right away, without playing a game, our backups already are in play.”

If Gaither can’t return for Week 2, look for Smith to bring in a veteran tackle following the Raiders game. It’s much more cost-friendly for a team to do so after the opener. If Smith were to acquire a veteran now, the contract would have to be guaranteed. Not so starting next week.

“There are some people of interest to us; we have some things going,” Smith says. “If we can find someone who we think can help us, we’ll let you know.”

Pure A.J. There are moments when he can’t help being John Wayne or Nobel sarcasm laureate.

“I do like the offseason we had and our draft picks,” he says. “We made a great effort to bring in the best backups out of the biggest free-agent pool I’ve seen. But it’s all a paper exercise so far. We’ll know at the end of the year how we did.

“But we can’t be left bleeding in the road like we were last year. If I had done a better job, maybe we only would have lost three in a row instead of six straight. I think we’ve had an outstanding offseason. Attendance (by players) was great, the attitude unbelievable. We had a phenomenal minicamp. I love the way we’ve prepared.”

So they have prepared. It used to be the Chargers were automatic picks to win the AFC West. No longer. Because their “elite” tag has vanished.

“When you don’t make the playoffs two years in a row you no longer are an elite team,” Smith says. “The people who assess that, looking at our last two years, it makes sense to me.

“But I want back in. I want in bad. It’s on now, brother.”

In that he’s his toughest critic, A.J. Smith doesn’t need enemies. All he needs is A. J. Smith.